Acryoyldimethyltaurine acid-based grafted copolymers

ABSTRACT

The invention provides water-soluble or water-swellable copolymers obtainable by free-radical copolymerization of  
     A) acryloyldimethyltaurine and/or acryloyldimethyltaurates,  
     B) if desired, one or more other olefinically unsaturated, optionally crosslinking comonomers containing at least one oxygen, nitrogen, sulfur or phosphorus atom and possessing a molecular weight of less than 500 g/mol, the copolymerization  
     C) taking place in the presence of at least one polymeric additive having a number-average molecular weight of from 200 g/mol to 10 9  g/mol.

[0001] The present invention relates to graft polymers based onacryloyldimethyltaurine and/or acryloyldimethyltaurates.

[0002] In recent years water-soluble polymers have acquired acontinually increasing importance in industry and science. In volumeterms, polyelectrolytes are occupying a very large proportion of theoverall annual production. They find application, for example, in paperprocessing, in the laundry detergents industry, in textile processing,in petroleum extraction or as important base materials for cosmetics.

[0003] In the cosmetics sector a key role is assigned topolyelectrolytes. Besides water-soluble surface-active substances thereis a high demand in this sector for systems which thicken oil and water.Thickeners of this kind, particularly the “superabsorbents” prepared onthe basis of polyacrylic acid, have progressed since their developmentin the 1970s to become a pillar of the hygiene sector. In theircrosslinked versions, partly or fully neutralized polyacrylic acids andtheir water-soluble copolymers are employed in numerous cosmeticformulations as bodying agents. The diversity of possible structures andthe diverse possible applications associated therewith are manifestednot least in a host of patents filed worldwide since the mid-1970s.

[0004] In the 1990s, innovative thickeners based onacryloyldimethyltaurine (AMPS) and the salts thereof were introducedinto the market (EP 816 403 and WO 98/00094). In both homopolymer andcopolymer form (®Aristoflex AVC, Clariant GmbH) such thickeners aresuperior in many respects to the corresponding polycarboxylates(Carbopols). For example, thickener systems based on AMPS displayoutstanding properties in pH ranges below pH 6, i.e., in a pH range inwhich it is no longer possible to operate with conventionalpolycarboxylate thickeners. Moreover, the microgel structure of suchthickeners leads to a particularly pleasant skin sensation. The ease ofprocessing and the favorable toxicological profile of the principalmonomer imbue these thickeners with a high application potential. Adisadvantage of acryloyldimethyltaurine-based thickeners is the frequentopalescence of their dilute aqueous gels. The cause of the opalescenceis the high degree of scattering of visible light at overcrosslinkedpolymer fractions which arise during the polymerization and which inwater are present only in an inadequately swollen form.

[0005] Surprisingly it has been found that grafted comb polymers basedon acryloyldimethyltaurine (AMPS) which are obtainable by conducting thepolymerization in the presence of a polymeric additive display theproperties of a thickener in a very good manner, and a clear appearance.

[0006] The invention provides water-soluble or water-swellablecopolymers obtainable by free-radical copolymerization of

[0007] A) acryloyldimethyltaurine and/or acryloyldimethyltaurates,

[0008] B) if desired, one or more other olefinically unsaturated,optionally crosslinking, comonomers containing at least one oxygen,nitrogen, sulfur or phosphorus atom and possessing a molecular weight ofup to 500 g/mol, the copolymerization

[0009] C) taking place in the presence of at least one polymericadditive having number-average molecular weights of from 200 g/mol to10⁹ g/mol.

[0010] The copolymers of the invention preferably possess a molecularweight of from 10³ g/mol to 10⁹ g/mol, more preferably from 10⁴ to 10⁷g/mol, very preferably from 5*10⁴ to 5*10⁶ g/mol.

[0011] The acryloyidimethyltaurates can be the organic or inorganicsalts of acryloyldimethyltaurine. Preference is given to the Li⁺, Na⁺,K⁺, Mg⁺⁺, Ca⁺⁺, Al⁺⁺⁺ and/or NH₄ ⁺ salts. Likewise preferred are themonoalkylammonium, dialkylammonium, trialkylammonium and/ortetraalkylammonium salts, in which the alkyl substituents of the aminesmay independently of one another be (C₁-C₂₂)-alkyl radicals or(C₂-C₁₀)-hydroxyalkyl radicals. Preference is also given to mono- totriethoxylated ammonium compounds with a different degree ofethoxylation. It should be noted that the invention also embracesmixtures of two or more of the above-mentioned representatives.

[0012] The degree of neutralization of the acryloyldimethyltaurine canbe between 0 and 100%, particular preference being given to a degree ofneutralization of more than 80%.

[0013] Based on the total mass of the copolymers, the amount ofacryloyldimethyltaurine and/or acryloyldimethyltaurates is at least 0.1%by weight, preferably from 20 to 99.5% by weight, more preferably from50 to 98% by weight.

[0014] As comonomers B) it is possible to use all olefinicallyunsaturated monomers whose reaction parameters allow copolymerizationwith acryloyldimethyltaurine and/or acryloyldimethyltaurates in therespective reaction media.

[0015] Preferred comonomers B) are unsaturated carboxylic acids andtheir anhydrides and salts, and also their esters with aliphatic,olefinic, cycloaliphatic, arylaliphatic or aromatic alcohols having acarbon number of from 1 to 22.

[0016] Particularly preferred unsaturated carboxylic acids are acrylicacid, methacrylic acid, styrenesulfonic acid, maleic acid, fumaric acid,crotonic acid, itaconic acid, and senecic acid.

[0017] Preferred counterions are Li⁺, Na⁺, K⁺, Mg⁺⁺, Ca⁺⁺, Al⁺⁺⁺, NH₄ ⁺,monoalkylammonium, dialkylammonium, trialkylammonium and/ortetraalkylammonium radicals, in which the alkyl substituents of theamines independently of one another can be (C₁-C₂₂)-alkyl radicals whichmay optionally be occupied by up to 3 (C₂-C₁₀)-hydroxyalkyl groups. Itis additionally possible to employ mono- to triethoxylated ammoniumcompounds with a different degree of ethoxylation. The degree ofneutralization of the carboxylic acids can be between 0 and 100%.

[0018] Further preferred comonomers are open-chain N-vinyl amides,preferably N-vinylformamide (VIFA), N-vinylmethylformamide,N-vinylmethylacetamide (VIMA) and N-vinylacetamide; cyclic N-vinylamides (N-vinyl lactams) with a ring size of 3 to 9, preferablyN-vinylpyrrolidone (NVP) and N-vinylcaprolactam; amides of acrylic andmethacrylic acid, preferably acrylamide, methacrylamide,N,N-dimethylacrylamide, N,N-diethylacrylamide, andN,N-diisopropylacrylamide; alkoxylated acrylamides and methacrylamides,preferably hydroxyethyl methacrylate, hydroxymethylmethacrylamide;hydroxyethylmethacrylamide, hydroxypropylmethacrylamide, and mono[2-(methacryloyloxy)ethyl] succinate; N,N-dimethylamino methacrylate;diethylaminomethyl methacrylate; acrylamido- and methacrylamidoglycolicacid; 2- and 4-vinylpyridine; vinyl acetate; glycidyl methacrylate;styrene; acrylonitrile; vinyl chloride; stearyl acrylate; laurylmethacrylate; vinylidene chloride; and/or tetrafluoroethylene.

[0019] Likewise suitable comonomers B) are inorganic acids and theirsalts and esters. Preferred acids are vinylphosphonic acid,vinylsulfonic acid, allylphosphonic acid, and methallylsulfonic acid.

[0020] The weight fraction of the comonomers B), based on the total massof the copolymers, can be from 0 to 99.8% by weight and is preferablyfrom 0.5 to 80% by weight, more preferably from 2 to 50% by weight.

[0021] Essential to the invention is that the copolymerization isconducted in the presence of at least one polymeric additive C), theadditive C) being added wholly or partly in solution to thepolymerization medium before the actual copolymerization. The use of twoor more additives C) is likewise in accordance with the invention.Crosslinked additives C) may likewise be used.

[0022] The additives C) or mixtures thereof must only be wholly orpartly soluble in the chosen polymerization medium.

[0023] During the actual polymerization step the additive C) has anumber of functions. On the one hand it prevents the formation ofovercrosslinked polymer fractions in the copolymer which forms in theactual polymerization step, and on the other hand the additive C) isstatistically attacked by active free radicals in accordance with thevery well-known mechanism of graft copolymerization. Depending on theparticular additive C), this results in greater or lesser fractions ofthe additive being incorporated into the copolymers. Moreover, suitableadditives C) possess the property of altering the solution parameters ofthe copolymers which form during the free-radical polymerizationreaction in such a way that the average molecular weights are shifted tohigher values. As compared with analogous copolymers prepared withoutthe addition of the additives C), those prepared with the addition ofadditives C) advantageously exhibit a significantly higher viscosity inaqueous solution.

[0024] Preferred additives C) are homopolymers and copolymers which aresoluble in water and/or alcohols. The term “copolymers” also comprehendsthose having more than two different monomer types.

[0025] Particularly preferred additives C) are homopolymers andcopolymers of N-vinylformamide, N-vinylacetamide, N-vinylpyrrolidone,ethylene oxide, propylene oxide, acryloyldimethyltaurine,N-vinylcaprolactam, N-vinylmethylacetamide, acrylamide, acrylic acid,methacrylic acid, N-vinylmorpholide, hydroxyethyl methacrylate,diallyldimethylammonium chloride (DADMAC) and/or[2-(methacryloyloxy)ethyl]trimethylammonium chloride (MAPTAC);polyalkylene glycols and/or alkylpolyglycols.

[0026] Particularly preferred additives C) are polyvinylpyrrolidones(e.g., K15®, K20® and K30® from BASF), poly(N-vinylformamides),poly(N-vinylcaprolactams), and copolymers of N-vinylpyrrolidone,N-vinylformamide and/or acrylic acid, which may also have been partly orfully hydrolyzed.

[0027] The molecular weight of the additives C) is preferably from 10²to 10⁷ g/mol, more preferably from 0.5*10⁴ to 10⁶ g/mol.

[0028] The amount in which the polymeric additive C) is used, based onthe total mass of the monomers to be polymerized during thecopolymerization, is preferably from 0.1 to 90% by weight, morepreferably from 1 to 20% by weight, and with particular preference from1.5 to 10% by weight.

[0029] In one further preferred embodiment the copolymers of theinvention are crosslinked, i.e., they contain comonomers containing atleast two polymerizable vinyl groups.

[0030] Preferred crosslinkers are methylenebisacrylamide;methylenebismethacrylamide; esters of unsaturated monocarboxylic andpolycarboxylic acids with polyols, preferably di-acrylates andtri-acrylates and -methacrylates, more preferably butanediol andethylene glycol diacrylate and -methacrylate, trimethylolpropanetriacrylate (TMPTA) and trimethylolpropane trimethacrylate (TMPTMA);allyl compounds, preferably allyl (meth)acrylate, triallyl cyanurate,diallyl maleate, polyallyl esters, tetraallyloxyethane, triallylamine,tetraallylethylenediamine; allyl esters of phosphoric acid; and/orvinylphosphonic acid derivatives.

[0031] A particularly preferred crosslinker is trimethylolpropanetriacrylate (TMPTA).

[0032] Based on the total mass of the copolymers, the weight fraction ofcrosslinking comonomers is preferably up to 20% by weight, morepreferably from 0.05 to 10% by weight, and very preferably from 0.1 to7% by weight.

[0033] The polymerization medium used may comprise all organic orinorganic solvents which have a very substantially inert behavior withrespect to free-radical polymerization reactions and whichadvantageously allow the formation of medium or high molecular weights.Those used preferably include water; lower alcohols; preferablymethanol, ethanol, propanols, iso-, sec- and t-butanol, very preferablyt-butanol; hydrocarbons having 1 to 30 carbon atoms, and mixtures of theaforementioned compounds.

[0034] The polymerization reaction takes place preferably in thetemperature range between 0 and 150° C., more preferably between 10 and100° C., either at atmospheric pressure or under elevated or reducedpressure. If desired the polymerization may also be performed under aninert gas atmosphere, preferably under nitrogen.

[0035] In order to initiate the polymerization it is possible to usehigh-energy electromagnetic rays, mechanical energy, or the customarychemical polymerization initiators, such as organic peroxides, e.g.,benzoyl peroxide, tert-butyl hydroperoxide, methyl ethyl ketoneperoxide, cumene hydroperoxide, dilauroyl peroxide or azo initiators,such as azodiisobutyronitrile (AIBN), for example. Likewise suitable areinorganic peroxy compounds, such as (NH₄)₂S₂O₈, K₂S₂O₈ or H₂O₂, forexample, where appropriate in combination with reducing agents (e.g.,sodium hydrogensulfite, ascorbic acid, iron(II) sulfate, etc.) or redoxsystems comprising as reducing component an aliphatic or aromaticsulfonic acid (e.g., benzenesulfonic acid, toluenesulfonic acid, etc.).

[0036] The polymerization reaction can be conducted, for example, as aprecipitation polymerization, emulsion polymerization, bulkpolymerization, solution polymerization or gel polymerization.Particularly advantageous for the profile of properties of thecopolymers of the invention is precipitation polymerization, preferablyin tert-butanol.

[0037] The polyfunctional polymers of the invention possess a greatstuctural diversity and, consequently, broad potential possibilities foruse, which can be tailored to virtually any task where interface effectsand/or surface effects have a part to play. Attention is drawn inparticular to the possibilities for application in the field ofcosmetology, as thickeners for example. The term “custom-tailoredpolymers” gives a vivid description of the possibilities which this newclass of polymer provides to the user.

[0038] Examples below are intended to illustrate the invention without,however, restricting it to them.

EXAMPLE 1

[0039] Reactants amount (g) NH₃-neutralized AMPS 80 t-Butanol 300 TMPTA1.8 Dilauroyl peroxide (initiator) 1 Poly-N-vinylpyrrolidone (® K-15,BASF) 5

[0040] The polymer was prepared by the precipitation method intert-butanol. The monomers in t-butanol were introduced as an initialcharge and the reaction mixture was rendered inert, and then, afterinitial heating, the reaction was initiated by addition of DLP. Thepolymer was isolated by removing the solvent under suction and bysubsequent vacuum drying.

EXAMPLE 2

[0041] Reactants amount (g) NH₃-neutralized AMPS 80 N-Vinylpyrrolidone 5Water 300 AMA 0.9 Na₂S₂O₈ (initiator) 1 Poly-N-vinylpyrrolidone (® K-30,BASF) 10

[0042] The polymer was prepared by the gel polymerization method inwater. The monomers were dissolved in water, the reaction mixture wasrendered inert, and then, after initial heating, the reaction wasinitiated by addition of sodium peroxodisulfate. The polymer gel wassubsequently comminuted and the polymer was isolated by vacuum drying.

EXAMPLE 3

[0043] Reactants amount (g) AMPS 80 Vinyl acetate 20 Cyclohexane 200Water 300 ® Span 80 1 Na₂S₂O₈ (initiator) 1Poly[N-vinylpyrrolidone-co-acrylic acid] (30/70) 4

[0044] The polymer was prepared by the emulsion method in water. Themonomers were emulsified in water/cyclohexane using ®Span 80, thereaction mixture was rendered inert using N₂, and then, after initialheating, the reaction was initiated by addition of sodiumperoxodisulfate. The polymer emulsion was subsequently evaporated downand by this means the polymer was isolated.

EXAMPLE 4

[0045] Reactants amount (g) NH₃-neutralized AMPS 80 t-Butanol 300N-Vinylformamide 20 TMPTA 1.8 ABAH (initiator) 1Poly[N-vinylcaprolactone-co-acrylic acid] (10/90) 10

[0046] The polymer was prepared by the precipitation method intert-butanol. The monomers in t-butanol were introduced as an initialcharge, the reaction mixture was rendered inert, and then, after initialheating, the reaction was initiated by addition of ABAH. The polymer wasisolated by removal of the solvent under suction and by subsequentvacuum drying.

EXAMPLE 5

[0047] Reactants amount (g) Na-neutralized AMPS 80 Water 300 TMPTA 1.8H₂O₂/iron (initiator) 1 Poly[N-vinylformamide] 8

[0048] The polymer was prepared by the solution method in water. Themonomers were dissolved in water, the reaction mixture was renderedinert, and then, after initial heating, the reaction was initiated bymeans of a suitable redox couple. The polymer solution was subsequentlyevaporated down and the polymer was isolated by this means.

[0049] Chemical designation of the products employed TMPTAtrimethylolpropane triacrylate AMA allyl methacrylate ABAHazobisamidopropyl hydrochloride AIBN azoisobutyronitrile

What is claimed is: 1) A water-soluble or water-swellable copolymerobtainable by free-radical copolymerization of A)acryloyldimethyltaurine and/or acryloyldimethyltaurates, and B) ifdesired, one or more other olefinically unsaturated, optionallycrosslinking comonomers containing at least one oxygen, nitrogen, sulfuror phosphorus atom and possessing a molecular weight of less than 500g/mol, the copolymerization C) taking place in the presence of at leastone polymeric additive having a number-average molecular weight of from200 g/mol to 10⁹ g/mol, prepared by precipitation polymerization intert-butanol.
 2. The copolymer as claimed in claim 1, further containingone or more comonomers B).
 3. The copolymer as claimed in claim 2,wherein the comonomers B) comprise unsaturated carboxylic acids, saltsof unsaturated carboxylic acids, anhydrides of unsaturated carboxylicacids, esters of unsaturated carboxylic acids with aliphatic, olefinic,cycloaliphatic, arylaliphatic or aromatic alcohols having 1 to 22 carbonatoms, open-chain N-vinyl amides, cyclic N-vinyl amides having a ringsize of from 3 to 9, amides of acrylic acid, amides of methacrylic acid,amides of substituted acrylic acids, amides of substituted methacrylicacids, 2-vinylpyridine, 4-vinylpyridine, vinyl acetate; styrene,acrylonitrile, vinyl chloride, vinylidene chloride, tetrafluoroethylene,vinylphosphonic acid or the esters or salts thereof, vinylsulfonic acidor the esters or salts thereof, allylphosphonic acid or the esters orsalts thereof and/or methallylsulfonic acid or the esters or saltsthereof.
 4. The copolymer as claimed in at least one of claims 1 to 3,wherein the polymeric additives C) are homopolymers and copolymers ofN-vinylformamide, N-vinylacetamide, N-vinylpyrrolidone, ethylene oxide,propylene oxide, acryloyldimethyltaurine, N-vinylcaprolactam,N-vinylmethylacetamide, acrylamide, acrylic acid, methacrylic acid,N-vinylmorpholide, hydroxymethyl methacrylate, diallyldimethylammoniumchloride (DADMAC) and/or [2-(methacryloyloxy)ethyl]trimethylammoniumchloride (MAPTAC); polyalkylene glycols and/or alkylpolyglycols.
 5. Thecopolymer as claimed in claim 4, wherein the polymeric additives C) arepoly(N-vinylformamides), poly(N-vinylcaprolactams), and copolymers ofN-vinylpyrrolidone, N-vinylformamide and/or acrylic acid.
 6. Thecopolymer as claimed in at least one of claims 1 to 5, which iscrosslinked.